Nested springs are used for various applications. For example, they can be used in the landing gear of airplanes, or on any type of device for securing fixtures to a relatively moving component. They have been used where reliability is paramount or in some situations to reduce the space envelope required where the spring is mounted. Examples of applications of nested springs are throttle return springs, brake return springs, and valve springs.
Often, nested springs are used to avoid single-point failures by providing a redundant system. They replace a single-spring system. In a single-spring system however, when the spring fails, the whole system fails. Having a dual spring system increases the factor of safety. If one spring fails, the other can still properly function for a time until the broken spring is replaced. In some cases, the springs wear, twist, or bend excessively where portions of the spring contact one another. The effect is worsened where the contact is acute, such as with a small contact surface area under high load. Also, some materials are abrasive, such as Titanium, and wear more quickly than other materials.